1. Technical Field
The present invention relates to a polarized light irradiating technology to be performed for photo alignment.
2. Background Art
In recent years, a technology referred to as Photo Alignment which is a technology for performing alignment by light irradiation when obtaining an alignment layer in an alignment film or an angle of view field compensation film of an liquid crystal display device exemplified principally by a liquid crystal panel has started to be employed. Hereinafter, the film or the layer in which alignment is caused by using the light irradiation is collectively referred to as photo alignment film. The term “alignment” or “alignment process” means giving a directional property to a certain property of an object.
Photo alignment is achieved by irradiating a film for photo alignment (hereinafter, referred to as a “film material”) with polarized light. The film material is formed of a resin such as polyimide, and the film material is irradiated with polarized light polarized in a desired direction (the direction to be aligned). With an irradiation of polarized light having a predetermined wavelength, a molecular structure (for example, a side chain) of the film material is aligned with the direction of the polarized light, so that a photo alignment film is obtained.
The photo alignment film is increased in size in association with an increase in size of liquid crystal panel in which the photo alignment film is used. Therefore, a required width of the irradiation area of the polarized light is increased to 1500 mm or wider. Examples of the polarized light irradiating apparatuses having a wide irradiated area includes an apparatus disclosed in Japanese Patent No. 4815995. The apparatus includes a rod-like light source having a length corresponding to the width of the irradiated area, and a wire grid polarized light element configured to polarize light from the light source, and is configured to irradiate a film material transported in a direction orthogonal to the longitudinal direction of the light source with polarized light.
In the polarized light irradiating apparatus for photo alignment described above, there are a case where an object (work) of the polarized light irradiation is a film material having a continuously extending elongated shape (hereinafter, referred to as an elongated work), and a case where a film material is already provided on a liquid crystal substrate and hence the liquid crystal substrate with a film material is a work.
Japanese Patent No. 4815995 discloses an apparatus in which the elongated work is wound into a roll, and an elongated work drawn from the roll is irradiated with polarized light. The elongated work irradiated with the polarized light at the time of roll-to-roll transport is cut at a predetermined position and adhered to the liquid crystal substrate. In contrast, as regards the polarized light irradiating apparatus configured to irradiate the liquid crystal substrate with the film material with the polarized light, no Cited Reference which discloses a configuration of an apparatus which has a performance of efficient processing (in a short tact time) is found.